Processes for effectively converting organics to carbon and steam have recently been disclosed. For example, co-pending PCT publication WO 2004/096456 A2 and U.S. patent publication 2004/0253166 A1 disclose means of delaquering, decoating, and recovering aluminum that is mixed with organics. Secondary aluminum occurs in these mixtures from many diverse sources, such as auto shredder residue, aluminum cans, waste particles of aluminum alloy and municipal waste. These resources represent very large potential sources of aluminum that are now only being exploited in very limited amounts.
There are two problems with these sources of aluminum metal that prevent the full recovery and use of these resources. First, the aluminum in foil and used beverage containers is very thin. When melted into a liquid aluminum at 700° C. using the conventional techniques, it is difficult to prevent substantial losses due to burning. Salt coverings are used to reduce these losses, but these coverings also become contaminated and therefore are another source of aluminum loses. Second, the material in auto shredder residue and municipal waste is a mixture of many different kinds of aluminum alloys and other metals such as copper and zinc. Many of these aluminum alloys are not compatible with each other and are harmed by the presence of other metals. A number of complex sorting and separation schemes are known, but they are expensive, inconclusive, and generally ineffective given the small particle size associated with metal recovery from these sources. Because of these problems, very large tonnages of secondary aluminum are currently exported to countries with low labor costs for stripping and sorting these diverse aluminum sources prior to purification. This practice of exporting these sources of aluminum results in a need to import very large amounts of purified aluminum.
Thus, to overcome these costly practices of shipping, sorting and importing secondary metals, there is a need for a process capable of efficiently recovering high yields of pure aluminum from low-grade, secondary sources that may be contaminated with other metals and/or organic materials. It would also be desirable to jointly recover valuable aluminum alloying materials such as magnesium and lithium as master alloys for recycle in these processes.